1. Field of the Invention
The present invention relates to a video information distribution system, and particularly, to a video dial tone service involving a video center, an exchange, and a communications network, for transmitting video information to homes and offices.
Conventional information services such as broadcasting and CATV provide users with programs at fixed hours. On the other hand, the video dial tone service allows individual users to (1) watch programs whenever they want to and (2) stop watching the programs and resume them later on. To realize this service, a video on-demand method is employed. The method allows each user to interactively specify a program kept in a video center and carry out start position specifying, fast-forwarding, and rewinding operations on the program.
2. Description of the Related Art
A conventional video dial tone service involves a video center storing a plurality of video sources. The video center provides user's video terminals with video information, i.e., video programs through a CATV network or a telephone exchange network. Users send network control signals to access the video center and watch video information such as movies at any time.
The video dial tone service may be achieved according to the on-demand method or a near on-demand method. The on-demand method allows a user to monopolize a program. Accordingly, the user can freely fast-forward and rewind the program. This method, however, has a disadvantage that a busy rate increases if many users simultaneously request the same program because the video center keeps a limited number of source programs. To solve this problem, the video center must keep many copies of the same program.
The near on-demand method compensates for the disadvantage of the on-demand method. This method sends a program to a plurality of channels with different start points so that a plurality of users may share the same program. When a user requests the program, a channel having the nearest start point at the time is allocated for the user. This method, however, has several disadvantages. Waiting time to the nearest start point becomes longer if the number of the channels is small. When a user carries out a fast-forward or rewind operation, the channels must be switched from one to another. At this time, video images widely jump from one to another if the number of the channels is insufficient. Namely, this method is incapable of carrying out precise control, and in particular, is unable to provide repeat and slow functions.